This invention relates to umbrellas or sunshades and more particularly to an outdoor umbrella of the stationary type generally known as a lawn umbrella, the shade having a noncircular periphery.
With the exception of the hyperbolic paraboloid umbrella illustrated in U.S. Pat. No. 3,252,469, the known prior art umbrellas generally include a shade having an inverted bowl configuration including a circular periphery supported by a multiplicity of struts or ribs emanating from the center. Although such constructions may be desirable for mobile hand held umbrellas which require rapid collapsibility, this requirement is not necessary for stationary lawn type umbrellas which are used generally as a sunshade. These umbrellas should have the capability of a readily adjustable shade to compensate for the relative movement of the sun during the day. Present umbrellas of this type, since they have a multiplicity of struts, require complicated articulating mechanisms and tiltable support poles to adjust the inclination of the shade. Such mechanisms not only add to the cost of the umbrellas, but they limit the aesthetic design available, the latter being an important element toward marketing a lawn type umbrella.